Her achievements included a theory of radioactivity (a term that she coined[5]), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies were conducted into the treatment of neoplasms, using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today. During World War I, she established the first military field radiological centres.

While a French citizen, Marie Skłodowska Curie (she used both surnames)[6][7] never lost her sense of Polish identity. She taught her daughters the Polish language and took them on visits to Poland.[8] She named the first chemical element that she discovered – polonium, which she isolated in 1898 – after her native country.[a]